The massive use of electronic devices such as electronic typewriters, computer keyboards or other data input electronic devices has brought about health problems that are associated with enormous amount of tiny and repeated motions of the wrists and the fingers of the user. Common complains that keyboard users mention include muscular fatigue, muscular dysfunction, rheumatic joint and tendon pains, numbness, tingling and sensation of burning.
Since the 1980's there are compelling evidences to the causative relationship between using keyboards, commutative trauma disorders (CTD's) and repetitive strain injuries (RSI's) such as carpal tunnel syndrome or flexor tendinitis.
RSI's and CTD's have three major causative mechanisms:                1. Muscular fatigue that results from isometric contraction. This usually affects the muscles in the back of the neck, the shoulder girdle, the anterior wall of the chest, the arms and the foreaems.        2. Compressive syndromes including traction and compression of nerves that their roots arise from the spine, nerve terminals median nerves that pass through the wrist in the carpal tunnel.        3. Overuse of tendons and tendon's sheaths reduces lubrication of these adjacent and integral tissues, thus bringing about rheumatic tendinitis that causes pain and dysfunction.        
Over the years, RSI's had spread from being an occupational hazard of professional users of keyboards and typists to lay people that use computers and enjoy browsing the web or chatting through e-mail. RSI's, whether from clicking the mouse or cocking the wrists left or right to reach for keys, is the major cause for the pursuit after ergonomic solutions.
The ergonomic solutions, in general, try to lessen the degree of ulnar deviation, shoulders and arms pinching, horizontally fixing the forearms in air and pressing the median nerve against the bony structure of the carpal tunnel. Patented ergonomic keyboards that maintain the standard arrangement of the usual keyboards are known in the art. An example is disclosed in U.S. Pat. No. 5,826,992 “Ergonomic Keyboard with Wrist Support” by Camacho and Granadino (1998). This ergonomic keyboard is provided with a top surface and a bottom surface and a front edge closer to the user, and a plurality of keys arranged in a plurality of adjacent rows. Each row includes a central arcuate portion, a left portion, and a right portion. The left and right portions extend tangentially from the arcuate portions. A wrist support extends along the front edge and a pair of legs pivotally mounted to the bottom surface elevate the wrist support from an underlying support surface. Another example of an arcuate keyboard is disclosed in U.S. Pat. No. 5,397,189 “Non-Planar Ergonomic Keyboard” by Minogue (1995). This ergonomic keyboard provides improved user comfort while maintaining a configuration sufficiently close to conventional keyboard. The keyboard is arcuate, with central keys situated closer to the user, and sloped in two directions. These ergonomic keyboards mean to lessen the fixation of the users forearms horizontally in air.
Other keyboards maintain also the QWERTY layout of the keys but divide the keyboard to two zones. Each zone is designated for each arm so that the wrists may be placed more conveniently. One example is disclosed in U.S. Pat. No. 5,372,441 “Ergonomic Keyboard Apparatus with Left and Right Key Section Separated by an Irregularly Shaped Space”, by Louis (1994). This patent discloses keyboard arrangement with a pair of angular disposed, spaced apart groups of character key dedicated for operating use respectively by the left hand and the right hand of a user. Another example of separated rather than spaced keys is disclosed in U.S. Pat. No. 5,612,691 titled “Ergonomic Keyboard” by Frank and Murmann (1997). This ergonomic keyboard comprises at least two housing sections with separate key pads wherein the two housing sections are interconnected by a joint permitting pivoting and also tilting of the two housing sections relative to each other. The user may pivot the housings to a comfortable position. These ergonomic keyboards purport to lessen the degree of ulnar deviation.
Another ergonomic keyboard aimed to reduce the likelihood of repetitive stress injuries is disclosed in U.S. Pat. No. 5,426,449 titled “Pyramid Shaped Ergonomic Keyboard” by Danziger (1995). The pyramid ergonomic keyboard comprised of three sets of keys or three adjustable keypads. A front keypad faces the operator and contains number keys, function keys and some more. The left and right keypads are at approximately a 45 deg. angle positioned in a tripod fashion. The left and right keypads each contain the key in standard QWERTY layout. Handrests protrude between the front keypad and the side keypads to support the hands while typing.
Whether conventional or ergonomic keyboard, all keyboards invented and patented up today employ the upper limbs from the shoulder girdle down to the tips of the fingers. As such, the upper limb function is biomechanically divided into two parts:                1. a “stabilizing arm unit” consists of the muscles of the upper back and the base of the posterior neck, the shoulders, the arms and forearms, all supposed to impart fingers stability. Stabilizing the long articulated arm is guaranteed through pinching shoulders opposite to the back of the neck and the upper spine of the chest, pinching arms against the sides of the body, and bending the elbows into a continuously weight bearing position, horizontally bearing the forearms and palms.        2. “striking probes unit” consists of the fingers, which carry out the ultimate task of hitting very accurately the chosen key.        
The wrists and fingers, backed up by the “stabilizing unit” through a flexible connection, use their natural movements of bending down towards the target key, key stroking one at the time. The thumbs usually employ only their up/down movements, neglecting their major movement, which is opposed to all other fingers as well as to the surface of the palm itself. In order to assure a better key stroking function, it is required to have a constantly stable “base” while the fingers are permanently moving, deviating and bending down. Moreover, one of the remain problems of the prior-art keyboards is that between strikes, the fingers are kept hanging over the keyboard in a stretched (overextended) and non-neutral position. In this position, the fingers have to be in an isometric contraction-demanding position, in order to avoid unwanted touch with the keys.
Regular keyboards encourage typist to twist and bend their hands in awkward positions that can add up to serious wrist injuries. Other contortion that may impose injury are combinations such as “function+control+key”. These combined key strokes force stretching the fingers unnaturally and painfully while typing, especially when the hands are small.
Fixed position had been accused of being the underlying mechanism of RSI's. In light of the biomechanism of typing as explained herein before, it is understandable why the keyboard is the most criticized component of the computer. The so-called ergonomic solutions for keyboards take into account a few but not enough solutions to reduce the risks of RSI's. Such solutions include, among others, keeping the fingers relaxed and smoothly arched while typing keeping the wrists relaxed as possible since the nerves and tendons that control the finger's movements are passing through narrow tunnels in the wrist area, using both hands in order to click on keys combinations, and using splints, pads and other supporting devices. The ergonomic keyboards and the supporting devices do not truly offer a comprehensive solution to lessen RSI'S. There is still a need to overextend the fingers, especially when trying to reach the distal raw of keys, there is still a need to support the wrist directly against the carpal tunnel and the stabilizing unit (neck-shoulders, shoulders-arms, arms-wrists) is still doing the task of key striking through a stiff-fixed position, known as a major reason to fatigue and injury.
Another disadvantage of the conventional and ergonomic keyboard is that the distance between the key rows is fixed. Therefore, it is suitable for a certain hand size. However, there is a difference between the hand of a child, a grown man or a teenaged girl, for example. There is a need to adjust the keyboard so that the distance between the key rows may be changed according to the user's hand size.